The knowledge you need to score high is not random.
If the short-finned fish swam to the other pond, it would be an example of natural selection.
The offspring of a fish in our hypothetical pond may have a genetic abnormality.
A new allele is created by themutation.
The allele frequencies in the offspring generation have changed because we have added a new one.
The basis of the variation we see in the first place is due to the fact that there is a very strong force when it is coupled with natural selection.
The first three factors act randomly with respect to the alleles in the population--which alleles increase and which decrease in frequency are determined by chance events.
The biggest mistake people make when thinking about natural selection is that it is synonymous with evolution.
The others are discussed in the previous section.
It is a major mechanism that has been instrumental in shaping the natural world.
It is not possible to pick a trait for or against if it is not inherited.
The condition states that there must be variation between parents in how many children they produce as a result of their different characteristics.
Natural selection can be illustrated with an example.
Before the Big Idea 1.A.2 tornado hit, there were short- and long-finned fish in the pond.
Natural selection is in the pond.
Longer fins allow a fish to swim faster.
The short-finned fish would be the fastest on the menu.
The long-finned fish, able to escape this new predator, would survive and reproduce.
We have created a situation in which the predator's presence results in a decrease in the short-fin allele and an increase in the long-fin allele, as a result of a nonrandom event.
There could be a decrease in the number of fish.
Natural selection random processes.
Different alleles give different advantages in different environments.
The environment--which includes everything from habitat, to climate, to competitors, to predators, to food resources--is constantly changing.
As the traits that give them an advantage also change, species are also constantly changing.
Fixed alleles can be seen in cases where a trait becomes beneficial; for example, all spiders have eight legs because the alternatives aren't as good.
Natural selection can occur when there are heritable characters that vary in fitness advantages and disadvantages on their host organisms.
The evolution section of the AP Biology exam contains research by Jean-Baptiste Lamarck and Charles Darwin.
The idea of evolution was proposed by Lamarck.
Lamarck proposed that giraffes evolved long necks because people were reaching for the leaves at the top of trees.
A giraffe had a long neck because of all the straining its parents did, and its offspring had a shorter neck because of it.
The key is that the trait was passed on from one generation to the next.
It is possible that the changed char acter could be passed on to the offspring.
The sex chromosomes that direct the production of offspring can't be changed after they are created.
It's not surprising that Lamarck confused genetic and environmental change because no one had discovered genes yet.
It is rumored that Darwin's book sat on his shelf, with the pages still uncut, until he died.
Wallace also came up with the idea of natural selection, but Darwin got the publication first and has become famous as a result.
Natural selection can include physical and intangible characteristics of organisms, such as eyes, fingernails, and livers.
The lifespan length is an adaptation.
Mating behavior has been selected by natural selection because it is an effective strategy.
A change in an individual's behavior is likely to affect their reproductive success.
The average male does worse than the individuals who try to court women by running at them, arms flailing, and screaming wildly.
A behavioral adaptation can evolve.
A good example is reproductive matu rity.
At the age of 13, females become reproductively mature.
Females that are mature at 12 are more likely to have problems with pregnancies.
Females who are 14 have lost valuable time, as their earlier-maturing peers have gained a year on them.
From generation to generation, females that matured at 13 became better represented in the population compared to slower and faster maturers.
We can see age at reproductive maturation as an adaptation because there will always be individuals that differ from the mode.
This happens when the population at one end of the spec is selected against the population at the other end.
The mean of a population is described.
When individuals at the two extremes of a spectrum of variation do better than the more common forms in the middle, selection is disruptive.
The snail shell color is disruptive.
Imagine an environment in which snails with dark shells are more likely to hide than those with light shells.
The forces of natural selection can change the frequencies of alleles.
Sexual selection and artificial selection complement natural selection.
There must be a reason why some individuals have greater reproductive success than others.
Natural selection includes both reproduction and survival.
Sexual selection is about access to mates.
In mammals and many nonmammalian species, females are limited in the number of offspring they can produce in their lifetimes, while males are not, because sperm are cheap to produce and few males participate in offspring care.
Males compete and females choose.
It makes sense that males have to compete because females are limiting resources, and it makes sense that females arechoosy because they invest a lot in each reproductive effort.
This leads to the evolution of characters that are designed for two main functions: (1) as weaponry or other tools for male competition and (2) as traits that increase mating opportunities because females prefer to mate with males who have them.
It is important to remember that female mate choice for certain characters is not random.
One hypothesis for why females choose males with colorful feathers is that they indicate good genes, which is important for a female's offspring.
Bright colors are costly, so a male with brightly colored feathers is probably healthy, which may indicate an ability to reduce parasites.
The "choosing males with colorful feathers" trait increases in the population because females who choose males that display honest indicators have more surviving offspring than females who don't.
Rather than allowing individuals to survive and reproduce as they would without human intervention, we may specifically select certain individuals to breed while restraining others from doing so.
Artificial selection has resulted in the domestication of a wide range of plant and animal species and the selection of certain characteristics.
This goes back and forth.
They are both responding in the same way to an environmental challenge, and this brings them closer together.
Even though insects are not related to birds, they both have wings in order to fly.
speciation can be caused by diverging evolution.
Two species have similar evolutionary changes.
They are responding in the same way.
Variation is one of the conditions for natural selection.
We talked about the mechanism by which evolution occurs.
New alleles can be introduced into a population by random changes in the DNA of an individual.
The discussion of why offspring are not identical to their parents can be found in Chapter 16 of Human Reproduction.
All individuals in a Big Idea 3.C.1 species or population have fixed characters, for example, all tulips develop from bulbs.
Tulips come in a variety of colors.
How balanced is maintained.
Big Idea 1.C.1 is the process by which new species evolve.
If the two populations change enough, they can't interbreed, even if the barrier is removed.
Even though there is no physical barrier, interbreeding ceases.
This may take many different forms.
A person has more than the normal number of chromosomes.
The individual can't reproduce with nonpolyploidic members of its species.
In some plants, it has resulted in new species because polyploidic individuals are only able to mate with each other.
The process was exemplified by Darwin's finches.
Several species will evolve if there are many ecological niches.
Evolutionary change is a constant happening in humans and other species.
As the environment changes, the allelic variation in these frequencies is highly variable.
If individuals who looked like them were to marry nonrandomly, the allele frequencies could change in a certain direction, and we would no longer be in equilibrium.
The test writers love to put an equation associated with the Hardy-Weinberg equilibrium on the exam.
The equation is used to determine if a population is in equilibrium.
The dominant condition is represented by 2.
The condition is represented by 2.
You are told that the population of the trees is 16 percent short and 84 percent tall, which is A, dominant.
They don't allow you to use a calculator.
These problems are easy to work with.
Do not despair.
You may be asked to give the percentages of the dominant and Heterozygous conditions in order to express the recessive trait.
If we find that the allele frequencies do not add up to one, then we need to look for the reasons for this, perhaps the population is too small and genetic drift is a factor.
The Hardy-Weinberg equilibrium has some important uses in evolutionary biology.
If they are similar, their host organisms came from a common ancestor, which means that they have evolved.
All bird species have the same bone structure.
The study of embryos shows remarkable similarities between organisms at the earliest stages of life, but the species look completely different as adults.
Human embryos have gills for a short time during early development.
embryology was an important piece of evidence used by Darwin.
At some point during an embryo's development, it will be like the adult form of all its ancestors before it.
The human embryo looks a lot like the fish embryo.
The conclusion from this is that embryologic similarity between developing individuals could be used.
The law rarely holds by the end of the 19th century.
Most organisms have characters that are no longer useful.
This should remind you of our discussion about why organisms are not adapted to their environments.
Sometimes an environment changes so much that a trait is no longer needed, but is not good enough to be eliminated.
The human appendix was listed as an example of vestigial characters in Darwin's original description of the process of evolution.
The physical manifestations of species that have gone extinct include bones.
The most important thing to remember is that adaptation is a result of natural selection.
Microevolution and macroevolution are different.
The typical pattern of macroevolution has disagreements in the field.
Gradualism versus equilibrium.
The debate continues.
The AP Biology exam includes questions on how life started.
Protobionts were formed from organic molecules.
The first Heterotroph gained ability cells and appeared when the Mutant appeared.
The O2 and ozone layer appeared.
Today's creation of eukaryotes is the result of natural selection.
The earth's atmosphere was formed.
NH3, CH4, H2O(g), and H2 were released from volcanoes.
The seas were formed.
As the earth cooled, the gases formed the seas.
Simple organic compounds appeared.
The energy from UV light, lightning, heat, radioactivity and other sources transformed the organic molecule into the inorganic one.
These may have been formed by dehydration.
These are formed from organic molecules and can carry out chemical reactions, but are unable to reproduce.
Heterotrophic prokaryotes appeared.
Heterotrophs consume organic substances to survive, since there was a limited amount of organic material, they competed and natural selection occurred, allowing for plenty of CO2 to be available.
The prokaryotes appeared.
The photo autotroph was a highly successful strategy compared to the heterotroph's, as it was able to produce its own food using light energy.
The ozone layer appeared.
The ozone layer blocks UV light from reaching the earth's surface because photosynthesis produces oxygen which interacts with UV light to form the ozone layer.
Life has evolved.
The variety of organisms that have existed throughout the earth's history was produced by natural selection.
Haldane believed that oxygen would have prevented the formation of a simple mole.
In the absence of oxygen, Stanley Miller and Harold Urey were able to form to support the hypothesis.
Large populations have more B.
Less chance for nat D. Gene flow ural selection is caused by more individuals.
The force of genetic drift is stronger in small populations.
Fruit fly wings last longer than B.
A male baboon has canine teeth.
A can be shaped by genetics.
It cannot be changed.
It specifically improves an C.
If it is E, the fitness of the organisms is affected.
It can be harmful to an animal.
There is only variation between individuals when there are two alleles.
The trait that is most common inbacteria is heritability.
The presence of O2 would have resulted in A.
The evolution of too many species too fast was caused by an earthquake.
The rate of interbreed would be slowed down if Oxygen had been present.
The ozone layer is formed by a new C in a flower plant.
A long winter causes a group of D.
All the oxygen was held in the volcanoes.
Individuals are moving out of an old range and into a new range, which leads to the decline of a spider species.
Each individual has an advantage to centage of the population's total genes because they represent a greater proportion of certain alleles.
All other factors are random.
If you have a population of genetic drift where there are 10 cheetahs and 3 die, you have lost 30 percent in size.
Fruit flies need to find more than 3 percent.
Equilibrium mates but also to survive.
The other characters are more likely to occur in large populations because they are sexually selected.
Natural selection can happen.
If the other three neces the basis of frequency, an allele becomes more sary conditions are met.
"Survival of the fittest" is an example of saying that certain increases.
It is not possible for the allele organisms to have higher reproductive success than other organisms.
Genetic drift is a change in frequencies as other frequencies are low.
Environmental change can be seen in Frequency- dependent selection.
Mutations in and of themselves are not caused by a random factor.
If evolution is going to occur, a mutation is also a random event.
A home range has taken the place of other elements in every shift because it is a highly behavioral change within an organisms lifetime.
There is a random process of evolution.
It is not possible to pick against Traits that are not inherited.
Speciation has occurred if two populations change so they can't interbreed.
Polyploidic individuals can't reproduce with nonpolyploidics.